Patent GB-425852-A (GB)
Title: Improvements in and connected with lifting jacks operated by liquid or fluid pressure and principally applicable to motor vehicles and other vehicles
IPC: B60S9/10
Filed: 1934-02-15
Abstract: 425,852. Lifting-jacks. KRUSE, M., 103, Grove Hill, South Woodford, London. Feb. 15, 1934, No. 5049. [Class 78 (iii)] [See also Group XXXI] A collapsable jack which may be mounted on a vehicle or used for other purposes comprises an extending linkage and fluid-pressure operating means therefor (hydraulic, air, or gas) mounted in a casing which forms a substantially closed housing for the linkage and the operating means when the jack is collapsed. As shown, the linkage folds alongside the fluid-pressure cylinder into a position substantially co-planar therewith. Several jacks may be mounted on a vehicle and controlled by one valve. Fig. 3 shows one jack in the extended position, and Fig. 2 shows a crosssection with the jack collapsed. The boxlike casing a, a<1> clamped on the vehicle axle b is open at the bottom and houses a fluidpressure cylinder f which slides over a fixed hollow plunger g and carries a cross-head o with rollers r running in guides s, t. A pair of struts u carrying a foot-plate y is pivoted on the cross-head and connected by links v with the casing a. The jack is extended by admitting pressure fluid to the hollow plunger at h, the cylinder f passing beneath a hinged cover n on the end of the casing. When the jack is collapsed, the struts u and links v fold alongside the cylinder and within the casing with the pivots lower than the dead centre, and the bottom of the casing is closed by a cover-plate 6 on the struts u and by the foot-plate y, the cover plate entering the end a<1> of the casing. The cylinder f is guided in a strap 5 which also forms a stop. Several jacks may be served by one pump 7, Fig. 6, operated by hand or by a motor, the pump being provided with a control valve 10 and a distributing valve 12. In the position shown, the valve 10 connects the pump cylinder with suction and delivery passages 20, 27 through ball check-valves 23, 24 in the valve ports. To maintain the jacks raised, the valve 10 is turned to a position with its ports out of register with the passages 20, 27. To lower the jacks, the valve 10 is turned to a third position in which a narrow longitudinal recess in the valve plug connects the passages 20, 27, or it may be turned to the position opposite to that shown and the liquid then pumped out of the jack cylinders and into the reservoir. In this way the pressure in the jack cylinders may be reduced below atmospheric after the jacks are collapsed, in order to hold the parts collapsed and to prevent rattling. The distributing valve 12 connects the pump delivery 27 by radial ports 29 with passages 26 leading to the jack cylinders. The valve may have five operative positions, one for admitting fluid to four jacks in order to raise a vehicle bodily, and four positions for operating each of the four jacks separately. The valve 12 may also provide for operating the jacks in pairs. The valves 10, 12 may be held in their various positions by spring- pressed bolts or by the ball-click devices 34, 32, which are used to indicate the correct positions of the operating handles. The valves 10, 12 may be operated from the dash-board. The pump cylinder is provided with a heavilyloaded relief valve 31a. The jack may be provided with a closing spring 3 acting on the links v, and with a spring in tension between the cylinder and plunger. In a modification, Fig. 9, (not shown), a catch pivoted on the struts u engages with a lug on the cylinder guide 5 to hold the struts in the collapsed position, and the cylinder is connected to the cross-head with lost motion so that it may move initially without moving the struts in order to engage the catch and release the struts. In this modification, the foot plate y is flush with the parts 5, 6 when the jack is collapsed, and the inlet passage for oil leads to the bottom of the plunger so that all the oil can be withdrawn in order to reduce weight and rattling. Specification 412,585, [Group XXXI], is referred to.